If you are currently an assistant in France and you would like to renew for a second year, the form is available online. You cannot change académies, but you can request to change school(s) and/or the city. You will need to get it signed by the chef d'établissement before sending it to the rectorat or CIEP. The deadline is March 14, 2011.
Even though the form says that you will receive an e-mail in June, do not count on this. Many times assistants do not hear anything concrete until September or even October because new assistants have priority over renewing assistants, and so the rectorat must wait until a new assistant resigns before offering the position to a renewing assistant.